The present invention relates to a process for preparing an extract from ivy leaves.
Extracts from ivy leaves are currently employed successfully in particular for the therapy of respiratory disorders because the extract shows spasmolytic, expectorant and antiobstructive effects. These effects are attributable in particular to the therapeutically important constituents of the ivy leaf extracts, which belong to the class of triterpene saponins.
The chief saponin in this connection is the bisdesmosidic hederacoside C and the α-hederin which is produced therefrom by ester hydrolysis. A further saponin which has been detected is hederagenin.
Since extracts from ivy leaves can be obtained by various processes, these extracts often display different potencies. This derives from the fact that the content of the constituents depends not only on the natural composition but also on the particular method for preparing the extract.
It has been possible to show in recent studies by the applicant that α-hederin is the really active substance in ivy leaves and contributes to the bronchospasmolysis because this substance causes relaxation of smooth muscles via binding to β-adrenergic receptors and cascades induced thereby.
Extracts from plant materials—especially dry extracts—and processes for preparing such extracts are described many times in the area of pharmacy and pharmaceutical preparations.
One process for preparing dry extracts from plant materials is disclosed for example in DE 101 12 168 A1. It is said that the content of lipophilic and hydrophilic substances can be adjusted using the process disclosed therein. In this case, the plant material is subjected to at least two extractions with solvents of different lipophilicity, and the extracts are obtained therefrom separately. The extracts are dried separately from one another and mixed in the desired ratio. It is possible in this way to adjust the content of lipophilic and hydrophilic substances. The process is said also to be suitable for obtaining dry extracts from ivy (Hedera helix).
However, this publication discloses neither an extract which has a specifically adjusted content of α-hederin and/or hederacoside C, nor a process with which such an extract could be provided.
Furthermore, DE 30 25 223 A1discloses a pharmaceutical preparation based on ivy extracts and a process for the preparation thereof, where the preparations rations include as active ingredient a 90% or 60% hedera saponin C-containing extract or α-hederin. The extract is obtained by using acetone and methanol. In order to convert hedera saponin C or hederacoside C into α-hederin, in order thus to obtain an extract with only α-hederin, in the said application the 90% extract is hydrolysed with sodium hydroxide or potassium hydroxide.
A process with which it is possible to prepare an extract in which α-hederin and hederacoside C are present in a content which can be adjusted as desired is, however, not disclosed in this publication either.
However, in order to ensure a reproducible therapeutic effect, it is precisely desirable to have ivy extracts which have a definable content of active ingredients.
A further disadvantage of extracts employed to date is that these extracts have to be administered more than once in order to have an immediate and lasting bronchospasmolytic effect inducible by α-hederin. The reason for this may be that the bioavailability of α-hederin is insufficient because, for example, the α-hederin content present in the extract is too low at the start of intake. On the other hand, α-hederin originally present in the extract is also absorbed relatively quickly in vivo, making multiple administrations necessary in order to achieve a therapeutic effect.
Taking account of the above statements, it is therefore an object of the present invention to provide a process for preparing an extract, and an extract by which a rapid bioavailability of α-hederin and maintenance of the bioavailability over a prolonged period is ensured.